Leak detection in water distribution systems using acoustic signals

ABSTRACT

Examples of a leak detection system are disclosed. In one example according to aspects of the present disclosure, a leak detection system includes a housing defining an interior, the housing connected to a component of a water distribution system. The leak detection system also includes a leak detection sensor contained within the interior of the housing and configured to detect a leak within the water distribution system. Additionally, the leak detection system includes a digital signal processing circuit in communication with the leak detection sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/939,942, filed Mar. 29, 2018, which is a continuation of nowabandoned U.S. application Ser. No. 14/870,070, filed Sep. 30, 2015,which is a continuation of U.S. application Ser. No. 13/492,790, filedJun. 8, 2012 which issued into U.S. Pat. No. 9,291,520, issued Mar. 22,2016, which claimed the benefit of U.S. Provisional Application61/523,274, filed on Aug. 12, 2011, all of which are hereby incorporatedby reference herein in their entireties.

FIELD

This disclosure relates to pipeline leak detection, and moreparticularly relates to detecting leaks in water distribution systems.

BACKGROUND

Water utility companies provide water to customers through a network ofwater pipes. The size of pipes may vary depending on the volume of waterthat is designed to flow through a particular section of pipe. Forexample, large water mains may provide water distribution in areas closeto the source of the water and the size of pipes may decrease as thedistance from the source increases. One concern for water utilitycompanies is the loss of water through leaks in the pipes. Not only doleaks waste clean potable water, but sometimes contaminants may beintroduced into the water supply from outside the pipes.

Due to the rapidly escalating costs of potable water, the scarcity offresh water supplies, and the increasing costs for water treatment anddistribution, minimizing leaks in water distribution systems is a goalof both public and private water distribution utilities. If a leak isnot particularly conspicuous, it may go undetected for months at a timewithout repair. It is therefore important to be able to detect leaksearly. One technique for detecting leaks is to measure pressure.However, a leak in a piping system may not necessarily produce a headpressure that appears as a change from normal pressures. The presence of“silent leaks” (undetected leaks) diminishes the value of a system thatdetects leaks based on head pressure since reducing leaks is the reasonwater companies install the system in the first place. In addition toallowing leaks to go undetected, another issue with existing leakdetection systems is the high rate of false alarms. A false alarm, forinstance, may cause extraneous and costly maintenance activity or it maydiminish the effectiveness of the detection system since operators maystart to ignore leak warnings. There is therefore a need for a leakdetection system that accurately detects leaks in a network of waterpipes.

SUMMARY

The present disclosure describes systems, methods, and devices fordetecting leaks in a pipe. According to an embodiment of the presentdisclosure, a leak detector is disclosed, wherein the leak detectorcomprises a sensor assembly that includes at least one sensor configuredto sense acoustic signals. The leak detector also includes at least oneprinted circuit board coupled to the sensor assembly. The printedcircuit board is configured to support a processing device, whichincludes at least a microcontroller unit and a digital signal processor.The microcontroller unit is configured to continually receive acousticsignals from the sensor assembly and the digital signal processor isconfigured to remain in a sleep mode except when the microcontrollerunit wakes the digital signal processor from the sleep mode atpredetermined times.

According to another embodiment of the present disclosure, a method isdisclosed. The method includes the steps of placing a digital signalprocessor in a sleep mode, wherein the digital signal processor isincorporated in a leak detector. The method also includes determiningwhether a request is received from a host to awaken the digital signalprocessor and awakening the digital signal processor when the request isreceived. In addition, the method includes the step of determiningwhether an urgent event related to a leak in a water main has beendetected by a microcontroller unit and awakening the digital signalprocessor when the urgent event is detected, and then enabling thedigital signal processor to analyze acoustic signals when awakened.

Various implementations described in the present disclosure may includeadditional systems, methods, features, and advantages, which may notnecessarily be expressly disclosed herein but will be apparent to one ofordinary skill in the art upon examination of the following detaileddescription and accompanying drawings. It is intended that all suchsystems, methods, features, and advantages be included within thepresent disclosure and protected by the accompanying claims.

DESCRIPTION OF THE FIGURES

The features and components of the following figures are illustrated toemphasize the general principles of the present disclosure.Corresponding features and components throughout the figures may bedesignated by matching reference characters for the sake of consistencyand clarity.

FIG. 1 is a block diagram illustrating a leak detection system accordingto various implementations of the present disclosure.

FIG. 2 is a block diagram illustrating a mesh network according tovarious implementations of the present disclosure.

FIG. 3 is a diagram illustrating an example of a water distributionsystem.

FIG. 4 is a diagram illustrating an example of leak in a main of a waterdistribution system.

FIG. 5 is a cross-sectional view of a leak detector of the currentdisclosure disposed in a nozzle cap of a fire hydrant in accord with oneembodiment of this disclosure.

FIG. 6 is a cross-sectional perspective view of the leak detector ofFIG. 5 in a nozzle cap, viewed from inside the hydrant.

FIG. 7 is a top view of a vibration sensor of the leak detector of FIG.5 in accord with one embodiment of the current disclosure.

FIG. 8 is a side view of two vibration sensors, as disclosed and shownwith reference to FIG. 7 , connected together using adhesive, in accordwith one embodiment of the current disclosure.

FIG. 9 is a cross-sectional view of a nozzle cap including the leakdetector of FIG. 5 .

FIG. 10 is a cross-sectional view of a leak detector of the currentdisclosure disposed in a nozzle cap in accord with one embodiment ofthis disclosure.

FIG. 11 is a perspective view of the inside of an enclosure in accordwith one embodiment of the current disclosure.

FIG. 12 is a perspective view of the inside of a leak detectionsubassembly in accord with one embodiment of the current disclosure.

FIG. 13 is a cross-sectional view of a leak detector in accord with oneembodiment of the current disclosure connected to a fire hydrant.

FIG. 14 is a close-up cross-sectional view of the leak detector of FIG.13 .

FIG. 15 is a close-up cross-sectional view of the leak detector of FIG.13 taken along the plane indicated by line 15 in FIG. 14 .

FIG. 16 is a cross-sectional view of the leak detector of FIG. 13 takenalong the plane indicated by line 16 in FIG. 14 .

FIG. 17 is a perspective view of the inside of a leak detectionsubassembly in accord with one embodiment of the current disclosure.

FIG. 18 is a block diagram illustrating a leak detection systemaccording to various implementations of the present disclosure.

FIG. 19 is a block diagram illustrating the host shown in FIG. 1according to various implementations.

FIG. 20 is a block diagram illustrating a leak detector according tovarious implementations of the present disclosure.

FIG. 21 is a block diagram illustrating the processing device shown inFIG. 20 according to various implementations of the present disclosure.

FIGS. 22A, 22B, and 22C are schematic diagrams illustrating theprocessing device shown in FIG. 20 according to various implementationsof the present disclosure.

FIG. 23 is a block diagram illustrating the digital signal processor(DSP) shown in FIG. 22C according to various implementations of thepresent disclosure.

FIG. 24 is a graph illustrating an example of signals detected by thesensor assembly shown in FIG. 20 .

FIG. 25 is a block diagram illustrating the communication device shownin FIG. 20 according to various implementations of the presentdisclosure.

FIG. 26 is a diagram illustrating a carrier board in accord with oneembodiment of the current disclosure.

FIGS. 27 is a flow chart of an initiation method in accord with oneembodiment of the current disclosure.

FIG. 28 is a flow chart of a monitoring method in accord with oneembodiment of the current disclosure.

FIG. 29 is a flow chart of a monitoring method in accord with oneembodiment of the current disclosure.

FIG. 30 is a flow diagram illustrating a method regarding sleep/waketimes of components of a processing device shown in FIG. 20 according tovarious implementations of the present disclosure.

FIG. 31 is a perspective view of a jig for punching mounting holes inaccord with one embodiment of the current disclosure.

FIG. 32 is a perspective view of a cup of the jig of FIG. 31 .

FIG. 33 is a perspective view of the cup of FIG. 32 .

FIG. 34 is a perspective view of a support of the jig of FIG. 31 .

FIG. 35 is a perspective view of a support of the jig of FIG. 31 .

FIG. 36 is a perspective view of a punch of the jig of FIG. 31 .

FIG. 37 is a top view of the punch of FIG. 36

FIG. 38 is a bottom view of the punch of FIG. 36 .

DETAILED DESCRIPTION

The present disclosure describes systems and methods for detecting leaksin a water distribution system. In the present disclosure, a distinctionmay be made between different sizes of water mains, for example, thosehaving a larger diameter and those having a smaller diameter. Usingacoustic data and pressure data that is sensed by various types ofsensors in contact with the water pipes, leaks can be detected. The leakdetection information can be communicated to the utility provider forfurther analysis. Depending on the type of leak, maintenance personnelmay be deployed to repair or replace leaky pipes in the waterdistribution system.

Minimizing leaks in the water distribution system is recognized as acritical success factor for water distribution utilities, especially dueto the scarcity of fresh water supplies, the cost of water treatment,and the costs for water distribution. The present disclosure provides anautonomous leak detection system that overcomes the limitedeffectiveness of existing leak detection systems with attendant highfalse alarm rates (dry hole) and undetected leaks. The water leakdetection systems and methods disclosed herein provide continuous leakdetection so that water utilities may be automatically alerted to pipebreaks in their system, allowing them to rapidly dispatch repair crewsto minimize customer service disruption and simultaneously minimizesub-surface damage.

Many municipal piping systems hold pressures in excess of severalhundred pounds per square inch (psi or lb/in²). When a leak forms in apiping member, the leaking water produces vibrations as it passes frominside the piping member to outside. Under the pressure of the municipalpiping system, vibrations in the piping member can be of frequencies inthe audible range and be of detectable amplitude. Most vibrations rangefrom 0 Hz to 3000 Hz.

The leak detection systems of the present disclosure are compatible withall distribution pipe types, including PVC pipes and PVC repair sleeves.The present systems have the ability to detect leaks as small as 1gallon per minute and can localize a leak to within several meters.Also, the present systems have a high accuracy rate as measured by thepercentage of leaks identified and a minimal percentage of false alarms.Another advantage of the present systems is the ability to providecontinuous monitoring for burst pipes or large leaks, which may requireimmediate attention.

In some embodiments, the systems and methods of the present disclosuremay provide surveillance of fire hydrants, which are attached to thewater distribution system, to alert the utilities of hydrant damage(e.g., from a vehicle accident) and hydrant tampering (e.g.,unauthorized water flow or water theft). The hydrant monitoring may alsoinclude determining if hydrant caps are stolen or if hydrants are openedto introduce foreign substances, sending immediate alerts when hydrantsare opened, detecting the closing of hydrants, sending updated statusalerts, providing a map of hydrant openings similar to OMS outages, etc.

Included below are embodiments of a device, a system, and a method for,among other functions, detecting leaks in pipelines. The system utilizesvibration sensors to detect leaks. In some embodiments, the vibrationsensors may be placed inside a housing. In some embodiments, the housingmay be a watertight housing. The system may be configured for use inboth wet and dry barrel hydrants in various embodiments. In someembodiments, vibration sensors may be placed inside a nozzle cap of thefire hydrant. In various embodiments, vibration sensors may be placedinside a bonnet of the fire hydrant.

This disclosure describes various embodiments of a device, method, andsystem for detecting leaks in piping members by sensing thepreviously-described vibrations in piping systems. The presentdisclosure describes sensing such vibrations using vibration sensorsdisposed in a fire hydrant.

FIG. 1 is a block diagram illustrating an embodiment of a leak detectionsystem 10. The leak detection system 10 comprises a server 13, anoperator system 14, a communication network 16, a client system 18, ahost 20, and a mesh network 22. The host 20 is configured to communicatewith a plurality of “nodes” of the mesh network 22. The nodes mayinclude leak detectors, and in some embodiments may also includecustomer meter devices, relay devices, system status detecting devices,and other communication devices. The nodes are configured forcommunicating leak detection information and/or utility information fromthe nodes or meter to the host 20.

According to various implementations of the present disclosure, the host20 may be configured to receive information from leak detectors, whichare connected within the mesh network, pertaining to the status ofvarious water pipes in a water distribution system of a water utilitycompany. The leak detectors may be configured to provide informationrelated to various measurements, such as acoustic, pressure, orvibration measurements. This information may be stored by the host 20for historic purposes for determining a baseline waveform indicative ofa properly operating water distribution system. When later signals arereceived that indicate excessive acoustic or vibration activity, thehost 20 may be configured to determine that a leak has been detected.

Also shown in FIG. 1 is a server 13 that may be configured to providemuch of the leak detection analysis to assist the host 20. The server 13may be part of the utility company (e.g., water utility company) andprovide communication with other users via the communication network 16.In some embodiments, the server 13 may be part of a company responsiblefor managing the utility measurement data or for providing monitoringservices for communicating issues (e.g., leaky pipes) in the utilityinfrastructure to the various utility companies. The communicationnetwork 16 in these embodiments may be a local area network (LAN), widearea network (WAN), such as the Internet, or any other suitable datacommunication networks. The communication network 16 may also includeother types of networks, such as plain old telephone service (POTS),cellular systems, satellite systems, etc.

The operator system 14 shown in FIG. 1 may represent a computer systemthat is operated by personnel of a company managing the leak detectionsystems and utility measurement devices within the mesh network 22. Insome respects, the operator system 14 may include an administrator forthe leak detection system 10. In some circumstances, as described inmore detail below, the user of the operator system 14 may be providedwith information indicating that an event has occurred that requiresimmediate response. For example, if a large leak, or burst event, hasoccurred in one of the water mains, resulting in a large amount of waterescaping from the mains, the user of the operator system 14 may need todeploy maintenance or repair personnel to resolve the burst issues. Theserver 13 and/or host 20 may detect extreme events, such as a burst in apipe, and provide an alarm to the operator system 14. The alarm may bein the form of an automated e-mail, a pop-up window, an interrupt signalor indication on a computer of the operator system 14, or other suitablemessage signifying an urgent event.

The client system 18 may include a computer system used by the utilityprovider. In this respect, the client system 18 may be a client of theadministration company that manages the utility measurement data and/orprovides monitoring services regarding the status of the utilityinfrastructure. The client system 18, therefore, may be able to receiveand to review status updates regarding the infrastructure. Alarms may beprovided to the client system 18, which may then be acknowledged andconfirmed. The client system 18 may also receive historic data andmanage the customer's accounts and usage information. In someembodiments, information may be provided to the client system 18 in aread-only manner.

FIG. 2 is a block diagram showing an embodiment of the mesh network 22of FIG. 1 , shown in a hierarchical configuration. Although the meshnetwork 22 may typically be distributed throughout a geographicalregion, the block diagram of FIG. 2 shows a hierarchy to emphasize theparent/child relationships among the various components. As illustrated,the mesh network 22 includes the host 20, a first level of intermediatenodes 34, a second level of intermediate nodes 36, a lowest level ofintermediate nodes 38, and meters 40. In some embodiments, theintermediate nodes 34,36,38 may include leak detectors for detectingleaks, where communication with the host 20 may include forwardinginformation up the hierarchy via other intermediate nodes 34,36,38 whichmay be on the same level or a different level. The intermediate nodes34,36,38 may be configured as stand-alone devices for assisting in thetransfer of data between the host 20 and leak detectors (or meters 40).The intermediate nodes 34,36,38 may also include a combination of leakdetectors and stand-alone devices. The mesh network 22 may include anynumber of levels X of intermediate nodes between the host 20 and themeters 40.

The host 20, intermediate nodes 34, 36, 38, and meters 40, according tovarious implementations, may comprise circuitry and functionality toenable radio frequency (RF) communication among the various components.The dashed lines shown in FIG. 2 may therefore represent RFcommunication channels between the different components. In otherembodiments, the devices may communicate with the host 20 by a cellularservice, via cellular towers and/or satellites. The wirelesscommunication between the devices 20, 34, 36, 38, and 40 may be activeduring some periods of time (when two respective devices are linked) andmay be inactive during other periods of time (when the devices are notlinked and/or are in sleep mode). Alternatively, any of the nodes may beconnected together through wired connections.

FIG. 3 is a diagram illustrating an example of a portion of a waterdistribution system 50. It should be understood that the portion of thewater distribution system 50 is shown merely as an example and does notnecessarily depict a specific water utility. The water distributionsystem 50 in this example includes a utility provider 52, such as awater utility company, and various water mains. The water mains includetransmission mains 54 (shown by thicker lines), which may include waterpipes having an inside diameter of at least twelve inches. The watermains also include distribution mains 56, which may include smallerpipes having an inside diameter of less than twelve inches. Thetransmission mains 54, having a greater size, may be configured to allowa greater amount of water flow in comparison with the distribution mains56. The transmission mains 54 may be located nearer to the utilitysource (e.g., utility provider 52) and the distribution mains 56 may belocated farther from the utility provider 52. In some systems,distribution mains 56 may be located along secondary roads orresidential roads. The water distribution system 50 also includes anumber of fire hydrants 58 (shown as dots), which are spaced along thedistribution mains 56. Although not shown, the fire hydrants 58 may alsobe tapped into the larger transmission mains 54. In some embodiments,the fire hydrants 58 may be spaced up to a distance of about 1,500 feetfrom each other.

According to various embodiments of the present disclosure, leakdetection devices may be attached to the fire hydrants 58. In someembodiments, leak detection devices may be attached to each hydrant 58while other embodiments may include attachment with about every otherone of the hydrants 58. In FIG. 4 , two adjacent fire hydrants 58 areshown, connected to the mains 54/56 for detecting a leak, such as leak60. Because of the nature of a water leak, such as leak 60, acousticsignals or vibration signals can be detected on the components (e.g.,mains 54 or 56, fire hydrants 58, etc.) of the water distribution system50. Particularly, leak detectors may be mounted on the mains 54/56themselves or may be mounted on the hydrants 58. When two adjacent leakdetectors, such as sensors mounted on hydrants 58 nearest to the leak60, are able to pick up acoustic signals with sufficient strength, thesignals may be used to detect the presence of a leak.

FIG. 5 shows a fire hydrant 58 with one embodiment of a leak detector100 of the current disclosure attached thereto. A nozzle cap 15 is shownattached by threading 21 to the hydrant threading 12 of the fire hydrant58. A nozzle cap gasket 23 helps seal the connection between the nozzlecap 15 and the fire hydrant 58. In some embodiments, the leak detector100 and the nozzle cap 15 will be included together as one system or maybe integrally formed in some implementations. Enclosure threading 25 ofthe nozzle cap 15 allows connection of attachment threading 105 of theleak detector 100. The leak detector 100 includes an enclosure 110, anantenna 120, an antenna cable 125, a battery 130, a circuit board 135,and at least one vibration sensor 150 a,c (150 b shown in other FIGS.,150 d referenced in other FIGS.) attached to the enclosure by at leastone bolt 155 a,c (155 b,d shown in other FIGS.). In various embodiments,a washer (not shown) may be inserted between the bolt 155 and thevibration sensor 150. In some embodiments, the washer is made of nylonor other nonconductive material to avoid contact of a metal bolt 155with electrical circuitry. In other embodiments, the bolt 155 may bemade of nonconductive material. In various embodiments, a washer (notshown) may be placed between each vibration sensor 150 and the enclosure110 to prevent contact with electrical circuitry.

The circuit board 135 includes preamplifiers for the vibration sensors150, audio codec processing, signal processing, and memory (includingRAM, ROM, programming memory, and storable media). Two circuit boards135 may be used in some embodiments. In some embodiments, one circuitboard 135 may be used for digital signal processing while anothercircuit board 135 may be used for radio frequency communications.

Any number of vibration sensors 150 a,b,c,d may be used in the leakdetector 100. Four vibration sensors 150 a,b,c,d are present in thecurrent embodiment. An eight vibration sensor 150 configuration has alsobeen tested. Any number of bolts 155 a,b,c,d may be used in variousembodiments, although four bolts 155 a,b,c,d—one per vibration sensor150 a,b,c,d—are present in the current embodiment. Also, otherattachment mechanisms are considered included within this disclosure. Invarious embodiments, the vibration sensors 150 will be coated in dampingmaterial although such material is not required. Sensor damping materialis chosen to dampen frequencies outside of a desired frequency rangewithin which leak detection is expected.

In order to repurpose the sensors 150 a,b,c,d, a predictable responsemust be generated. Piezoelectric material is highly responsive toalterations. As such, mounting holes 158 (shown in FIG. 7 ) in thesensors 150 a,b,c,d are repeatably positioned precisely in the center ofeach sensor 150 a,b,c,d. A jig 1200 (shown in FIG. 31 ) has been createdto effect a repeatable mounting hole 158 by punching through thevibration sensor 150, as described elsewhere in this disclosure.

The enclosure 110 may be made of plastic, metal, or other generallyrigid materials. Because the leak detector 100 of the current embodimentincludes an antenna 120 and, thereby, is intended to transmit wirelesssignals, the enclosure 110 may be made of non-ferrous materialsincluding brass, plastic, bronze, and aluminum, among others. However,the antenna 120 protrudes from the enclosure 110, and, as such,interference by the enclosure 110 may be minimal in some embodiments.

As seen in FIG. 6 , each vibration sensor 150 a,b,c,d in the currentembodiment is bolted onto the nozzle cap 15 using one bolt 155 a,b,c,d,respectively. Each vibration sensor 150 a,b,c,d includes piezoelectricmaterial. Piezoelectric material generates an electric current inresponse to bending. With vibration, piezoelectric material generates acurrent in response to the vibration. In some embodiments, eachvibration sensor 150 a,b,c,d has a resonance frequency that is tuned toan anticipated frequency of vibrations generated by an anticipated leakin a piping member. The resonance frequency may be tuned in someembodiments and may not be tuned in others.

As seen with reference to FIG. 7 , one embodiment of the vibrationsensor 150 of the current embodiment is shown. The vibration sensor 150includes three components. A base 152 provides a substrate fordeposition of other components of the vibration sensor 150. In thecurrent embodiment, the base 152 is a disc and is made of brass;however, various materials and shapes may be used in variousembodiments. Deposited onto the base 152 is a piezoelectric layer 154that is composed of piezoelectric crystals. Deposited above thepiezoelectric layer 154 is a conduction layer 156 that is made of aconductive material deposited on the surface of the piezoelectric layer154. Although the piezoelectric layer 154 appears as a ring from theview of the current FIG. 7 , the piezoelectric layer 154 extends fullybelow the conduction layer 156.

As stated elsewhere in this disclosure, the piezoelectric materialproduces electrical charge in response to bending, and a waveform ofcharge may be produced when the piezoelectric material is exposed tovibration. As such, a charge differential between the conduction layer156 and the base 152 upon bending of the piezoelectric material may beused to sense the vibrations to which the piezoelectric layer 154 hasbeen exposed. Therefore, leads 157 a,b are soldered to the base 152 andthe conduction layer 156, respectively. The leads 157 a,b allowconnection to a processing device or another electrical device so thatthe charge differential may be handled electronically, which may includerecordation, amplification, summation, digital processing, and a numberof other electrical features, described elsewhere in this disclosure. Amounting hole 158 is seen in the vibration sensor 150 and is produced asreferenced elsewhere in this disclosure. In the current embodiment, thepiezoelectric layer 154 and the conduction layer 156 are found on onlyone side of the base 152. However, other configurations may be seen invarious embodiments.

FIG. 8 shows a side view of two vibration sensors 150′ and 150″connected together in back-to-back arrangement in accord with oneembodiment of the current disclosure. The profile of each vibrationsensor 150′,150″ can be seen. Each vibration sensor 150′,150″ includesthe base 152′,152″, the piezoelectric layer 154′,154″, and theconduction layer 156′,156″. The thickness of any layer as shown in thecurrent embodiment is for exemplary purposes only and should not beconsidered to scale or in any way limit the scope of this disclosure. Inthe current embodiment, a strip of adhesive 161 is seen between the twovibration sensors 150′,150″. In various embodiments, the adhesive 161may be double-sided tape, various glues, various coatings includingelastomeric and silicon coatings among others, and pure adhesives. Insome embodiments, an adhesive layer may not be included. In suchembodiments, a non-conducting spacer may be used, such as a nylon orrubber spacer.

Turning to FIG. 9 , electrical connections (such as leads 157 a,b inFIG. 7 ) connect each vibration sensor 150 a,b,c,d with the circuitboard 135. Wires form the electrical connections in the currentembodiment. A partition 410 (not shown) may be included within theenclosure 110 to separate the vibration sensors 150 a,b,c,d from thebattery 130 and the circuit board 135. A mating enclosure 305 isincluded to house the battery 130 and the circuit board 135. The matingenclosure 305 may be connected to the enclosure 110 in several ways,including an integrated construction, plastic welding, threading,snap-fit, and key/fit arrangements, among others. A mating gasket 350helps seal the connection of the enclosure 110 and the mating enclosure305.

The battery 130 and the circuit board 135 may be encased in waterproofor water-resistant material—also known as “potting”—such as epoxy,resin, sealant, or RTV, among others. This potting provides severaladvantages, among them providing a water barrier and providingstructural integrity in what may be an extremely high pressureenvironment—as previously noted, more than several hundred psi. Thebattery 130 and circuit board 135 may be encased individually in someembodiments. In other embodiments, the mating enclosure 305 will includea pot of waterproof or water-resistant material put inside the matingenclosure 305 after the battery 130 and the circuit board 135 are placedinside. However, the vibration sensors 150 a,b,c,d are not restrainedfrom vibration and are not encased within such material, as suchmaterial may provide unwanted dampening of vibrations. As such, thepartition 410 (not shown) serves to separate the items to be encased inwaterproof or water-resistant material from the vibration sensors 150a,b,c,d. If the partition 410 is included, it will include at least onehole (not shown) to allow wires to form the electrical connections. Theantenna cable 125 also connects to the circuit board 135. In someembodiments, the battery 130 and circuit board 135 are encased inwaterproof material before the mating enclosure 305 is connected to theenclosure 110.

As can be seen in FIG. 9 , in the current embodiment, the enclosure 110does not enclose all of the features of the leak detector 100. Anantenna enclosure 320 is placed over the antenna 120 in the currentembodiment. The antenna enclosure 320 is separate from the enclosure 110in the current embodiment. The antenna 120 protrudes out of the nozzlecap 15. This protrusion aides in allowing the antenna 120 to communicatewireless signals without interference from the nozzle cap 15, theenclosure 110, or other features of the fire hydrant 58 while stillprotecting the antenna 120 from tampering or from environmental factors.Typically the nozzle cap 15 is made of cast iron, which may interferewith wireless signal transmission. The antenna enclosure 320 is made ofa material that does not interfere with wireless signals, includingnon-ferrous materials such as brass, bronze, or plastic, among others.In the current embodiment, the antenna enclosure 320 is made of plastic.The antenna enclosure 320 includes a bell portion 324, a shaft portion326, and a retention ring 328. To place the antenna enclosure 320 intothe assembly of the leak detector 100 and nozzle cap 15, the antennaenclosure 320 is press-fit into the nozzle cap 15. The nozzle cap 15includes a joining portion 335. The joining portion 335 in the currentembodiment is a shelf inset to the inside of the nozzle cap 15. When theantenna enclosure 320 is pressed into the nozzle cap 15, resilience ofthe plastic allows the shaft portion 326 and retention ring 328 to bendinwardly with respect to the bell 324. Once the retention ring 328passes the joining portion 335, the resilience of the plastic allows theantenna enclosure 320 to snap back to its original shape, therebyallowing the retention ring 328 to prevent the antenna enclosure 320from being pulled out. An antenna enclosure gasket 340 seals theconnection between the antenna enclosure 320 and the nozzle cap 15.Other connection interfaces are included in this disclosure, includingthreading, welding, and sealing with plastic cement, RTV, or similarmaterials, among others.

Enclosure threading 25 of the nozzle cap 15 interacts with attachmentthreading 105 to secure the enclosure 110 to the nozzle cap 15. Anenclosure gasket 345 helps seal the connection between the enclosure 110and the nozzle cap 15.

The leak detector 100 operates by sensing vibration in the pipingsystem. The piping system translates vibrations produced by leaksthroughout piping members in the system. Moreover, the ground mayconduct some vibrations as well. The vibrations are translated throughthe piping system, particularly through the rigid materials making upthe system, including cast iron piping. This translated vibrationtravels through the piping system to the fire hydrant 58, into thenozzle cap 15 through its connection with the fire hydrant 58, into theenclosure 110 through its connection with the nozzle cap 15, into thebolts 155 a,b,c,d through their connections with the enclosure 110, andinto the vibration sensors 150 a,b,c,d through their connections to thebolts 155 a,b,c,d. Although the mechanical translation of vibrationsdescribed above provides sufficient vibration for detection of leaks,the piping system may also translate acoustic vibration which may besufficient of itself to allow detection by the vibration sensors 150 aswell.

When vibration is translated into the vibration sensors 150 a,b,c,d, thepiezoelectric material generates an electronic current. The current istransmitted to the circuit board 135 where it is processed as thedetection of a leak. The detection of a leak can then be communicated toa remotely located communicator or host by the system. In variousembodiments, sensors 150 a,b,c,d may be all aligned in a stackedarrangement on one bolt 155′ (not shown) and mounted to one point onenclosure 110. This stacked arrangement may have a different responsefrom other orientations. Various other orientations may be used as well.

In operation, the leak detector 100 may be configured to operate and todetect leaks at all times. However, to preserve battery life, the leakdetector 100 may also be configured to awaken on timed intervals tomonitor whether vibrations are present in the system. For example, theleak detector 100 may awaken on 5-minute intervals in some embodimentsor on 10-minute intervals in other embodiments. In some embodiments, theleak detector 100 will be configured to awaken only at night, or onlywhen background noises are at a minimum. The leak detector 100 may thenreturn to sleep state, which may include all or a portion of thecircuitry to be completely or partially unpowered or in a low powerstate. The timing of the interval may be determined by programming. Ifthe leak detector 100 determines that a leak is present in the system,the leak detector 100 may be configured to send a distress signal to aremotely located communicator or host and/or to store such leakdetection data for later transmission.

Elimination of noise is effected by amplification of sensor data becausenoise is random and not cumulative, whereas harmonic oscillation iscumulative and additive. Thus, when sensor output is added together forthe four-sensor arrangement, noise does not amplify but harmonicoscillation does. The result is that the multiple-sensor arrangementeffectively cancels noise from the amplification or renders theamplitude of noise so small as compared to harmonic oscillation in thesystem that such noise is negligible.

The leak detector 100 has a relatively high signal-to-noise ratio. Thehigh value of signal-to-noise ratio comes from two sources. First, noiseis random and does not add, as described above. Second, because the leakdetector 100 includes amplification, it is capable of detecting a lowerthreshold because a higher amplitude requires less amplification for aquality signal. As such, noise is not amplified because higher amplitudevibrations are detected more easily.

With piezoelectric transducers, output generated by the piezoelectricmaterial is relative to the “quality” of the piezoelectric material,which is affected by the size of the crystal making up the material.Large responses are typically seen from higher quality transducers.Although the leak detector 100 can function with high-qualitypiezoelectrics, vibration sensors 150 a,b,c,d in the current embodimentare relatively low-cost piezoelectric transducers. In the currentembodiment, vibration sensors 150 a,b,c,d are repurposed outputtransducers, not input transducers. The vibration sensors 150 a,b,c,dand array are chosen to provide a low-cost alternative to sensors thatmay require higher-quality, more expensive transducers. The vibrationsensors 150 a,b,c,d of the current embodiment can be mass-produced at alower cost leading to a lower cost end product. Although piezoelectrictransducers are used in the current embodiment, other types oftransducers may be used in various embodiments to convert mechanicalvibration into electrical signals, including electromagnetic transducers(such as solenoids and speaker technology), laser measurement ofvibration of a surface, microelectromechanical systems (MEMS), andothers.

The leak detector 100 may be in communication with a mesh network orother communications network to send and to receive wirelesscommunication of data. Such systems are described in more detailelsewhere in this disclosure. The leak detector 100 may also have thecapability to store or to log leak detection data until the leakdetector 100 is able to be checked, either manually or electronically.In one embodiment, the leak detector 100 may log over one month's worthof leak detection data which may then be downloaded and analyzedmanually or via a wireless communication device by a person responsiblefor inspecting pipelines. To store the leak detection data, in variousembodiments the leak detector 100 may include internal memory configuredto store the leak detection data for download at a later time. Internalmemory may include a hard drive, flash memory, or other various datastorage devices or systems.

As previously disclosed, an array of leak detectors 100 may be usedthroughout a piping system. For example, a leak detector 100 may be usedon each fire hydrant 58 in the piping system (as, for example, in FIGS.3 and 4 ). Such a configuration may address leaks on piping members thatare geographically remote to a particular vibration sensor 150. Also,such a configuration would allow maintenance workers to isolate a regionof piping in which a leak is most likely present by determining whichleak detectors 100 in the network have the largest amplitude ofvibrations.

Testing was performed comparing the response of plastic and metalenclosures 110. Acetyl plastic was used for testing. The response of thevibration sensors 150 was relatively similar for both metal and plasticenclosures 110. In some cases the low frequency response (below 10 Hz)of the vibration sensors 150 in the plastic case was lower in magnitudeor amplitude than that of the metal case, but this response is notconsistent.

FIG. 10 shows another embodiment of a leak detector 100′. The currentembodiment includes vibration sensors 150 a′,b′,c′,d′ (150 d′ not shown)disposed on bolts 155 a′,b′,c′,d′ (155 b′,d′ not shown) which arescrewed into an enclosure 110′. In the current embodiment, the bolts 155a′,b′,c′,d′ allow the vibration sensors 150 a′,b′,c′,d′ to float inspace as opposed to bolting down. A mating enclosure 305′ includesthreading 420 which allows a connection with threading 425 on theenclosure 110′. The connection is sealed by the mating gasket 350. Themating enclosure 305′ includes a connection nut 430 that allowstightening of the mating enclosure 305′ into the enclosure 110′ using awrench or other tool.

The leak detector 100′ includes two circuit boards: a radio frequency(RF) board 136′ and a digital signal processing (DSP) board 137′.Electronics on the RF board 136′ and the DSP board 137′ will be similarto the electronics contained on circuit board 135 in the leak detector100. The partition 410 can be seen in the view of the currentembodiment. An antenna cable 125′ connects the antenna 120 to the RFboard 136′. Although not shown, the battery 130 is connected to both theRF board 136′ and the DSP board 137′. In some embodiments, the battery130 may be connected to one of the RF board 136′ and the DSP board 137′which then connects the power from the battery 130 in series to theother board.

Another embodiment of an enclosure 1110 is seen in FIG. 11 . Theenclosure 1110 includes five posts 1155 a,b,c,d,e protruding from aninner surface 1112 of the enclosure 1110. The posts 1155 a,b,c,d,e ofthe current embodiment are spaced a consistent distance apart but arenot equally distributed about a circumference of the inner surface 1112.Instead, the posts 1155 a,b,c,d,e of the current embodiment are spacedso that more posts 1155 a,b,c,d,e are on one half of the enclosure 1110than on the other. In other embodiments, equidistant spacing may beused. In various embodiments, more or fewer posts 1155 may be used.

The posts 1155 provide some rigidity to the enclosure 1110 that aids inseveral ways. Among other benefits, the posts 1155 provide addedstrength to the enclosure 1110 in what may be an ultra-high pressureenvironment (exceeding several hundred psi, as previously noted).Additionally, the posts 1155 provide a structural restraint againstresonance of the enclosure 1110 so that resonance frequencies seen inthe enclosure 1110 do not distort leak data observed by vibrationsensors 150.

The posts 1155 also serve as mounting locations for the vibrationsensors 150. In the current embodiment, each post 1155 a,b,c,d,eincludes a retaining ring 1157 a,b,c,d,e and mounting bore 1159a,b,c,d,e that is threaded. The retaining ring 1157 a,b,c,d,e is acountersink channel into which a nylon washer (not shown) can be placed.The nylon washer allows the vibration sensors 150 to be mounted withoutallowing electrical conductivity between the enclosure 1110 and eachvibration sensor 150. Although the current embodiment displays aretaining ring 1157 a,b,c,d,e on each post 1155 a,b,c,d,e, variousembodiments include various configurations and may omit the retainingring 1157 a,b,c,d,e from some or all of the posts 1155 a,b,c,d,e.Additionally, although five posts 1155 a,b,c,d,e are shown in thecurrent embodiment onto which a vibration sensor 150 may be mounted,various configurations may be made for mounting vibration sensors 150.For example, in some embodiments, more than one vibration sensor 150 maybe mounted on one post 1155 while another post 1155 may include novibration sensor 150 mounted.

A leak detection subassembly 1111 is shown in FIG. 12 . Theconfiguration shown represents only one embodiment of the currentdisclosure among many. The leak detection subassembly 1111 shows theinterrelationship of several parts in one embodiment of the disclosure.The leak detection subassembly 1111 of the current embodiment includesfive vibration sensors 150 a,b,c,d,e. As can be seen, vibration sensors150 a and 150 b are connected by bolt 155 b of the current embodiment.In the current embodiment, the bolt 155 b is made of nylon. Bothvibration sensors 150 a,b are connected along one post 1155 b. Vibrationsensors 150 a,b are connected together using adhesive 161 (seen in FIG.8 ) between them, as previously described with reference to FIG. 8 ,although the vibration sensors 150 a,b, of the current embodiment may bearranged back-to-back (as seen in FIG. 8 ) or face-to-back. In variousembodiments, the adhesive 161 may be double-sided tape, various glues,various coatings including elastomeric and silicon coatings amongothers, and pure adhesives. In some embodiments, an adhesive 161 may notbe included. In such embodiments, a non-conducting spacer may be used,such as a nylon or rubber spacer. In other embodiments, conduction maynot be a concern if the base 152 a,b of each vibration sensor 150 a,bwere connected to the same ground. However, the use of an adhesive 161may provide damping of the vibration sensors 150 to prevent resonancealong the natural frequency of each base 152 or, if different, of eachvibration sensor 150. As such, the configuration of the currentlydescribed embodiment allows some damping of resonance between thevibration sensors 150 a,b because they are mechanically restrained bythe adhesive 161. In some embodiment, individual vibration sensors 150may be coated with a vibration damping layer that may be composed ofvarious substances, including silicone, elastomer, various polymers,various resins, various rubbers and synthetic rubbers, various vapordepositions, and various coatings. In one embodiment, Loctite RTV 5140has been used as a coating with success. Loctite 5150 adhesive sealanthas also been used with success.

The leak detection subassembly 1111 displays but one possible embodimentthrough which the vibration sensors 150 may be arranged in the enclosure1110. In various embodiments, the arrangement of the various componentsmay change as may be included elsewhere in this disclosure. Moreover,the leak detection subassembly 1111 does not include other parts ofvarious leak detectors (i.e., 100,100′,3100). However, the leakdetection subassembly 1111 may be included in various forms within thevarious embodiments as disclosed herein.

Vibration sensors 150 d,e are connected together along post 1155 d usingbolt 155 d with the same or a similar configuration to vibration sensors150 a,b. However, vibration sensor 150 c is connected alone to post 1155c (not seen in FIG. 12 , but seen with respect to FIG. 11 ) using bolt155 c. Vibration sensor 150 c in some embodiments is a burst or tampersensor. As described elsewhere in this disclosure, leak detectors of thecurrent disclosure may be configured to monitor for leak detectioncontinuously, may be configured to monitor on a wake/sleep basis, or maybe configured to do both. When vibration sensor 150 c is used as a burstor tamper sensor, it is continuously monitored to detect a pipe burst ora tamper event even if other vibration sensors 150 a,b,d,e are monitoredon a sleep/wake schedule. The vibration sensor 150 c, as acontinuously-monitoring sensor, is capable of detecting a pipe burst ortamper event, thereby causing other sensors 150 a,b,d,e to wake up (ifnecessary) and allowing communicating of the pipe burst or tamper eventto a remote host.

In the current embodiment, a summation board 1113 is seen mounted underthe vibration sensor 150 c. The summation board 1113 allows manualsummation of the piezoelectric current generated from the vibrationsensors 150 a,b,c,d,e or, in another embodiment, of vibration sensors150 a,b,d,e. Each vibration sensor 150 a,b,c,d,e is connected to thesummation board 1113 which provides a passive, manual summation of thevibration sensors 150 a,b,c,d,e. In various embodiments, the signals ofeach vibration sensor 150 a,b,c,d,e may be individually communicated toa remote host that performs the summation function.

Summation of vibration sensors 150 a,b,c,d,e may include an electronicamplifier in some embodiments. However, in some embodiments, electronicamplification may not be necessary. Since piezoelectric material mayprovide a positive current when deflected in one direction and anegative current when deflected in the opposite direction, it becomesimportant to know which deflection causes positive charge and whichdeflection causes negative charge. When two sets of piezoelectricmaterial produce the same charge (either positive or negative, but notnecessarily the same amplitude) with the same deflection, they are saidbe “in-phase.” When two sets of piezoelectric material produce oppositecharges with the same deflection, they are said to be “out of phase.”The manual summation referenced above is achieved by connecting thevibration sensors 150 a,b,c,d,e in such a way that the output waveformscreated by the piezoelectric material are in phase and positive chargeis added to positive charge while negative charge is added to negativecharge. Thus, it becomes important to know whether the vibration sensors150 a,b,c,d,e are in-phase or out of phase with each other. If thevibration sensors 150 a,b,c,d,e are connected as in-phase but are out ofphase, vibration sensors 150 a,b,c,d,e will cause a cancellation of atleast some of the charge generated by other vibration sensors 150a,b,c,d,e with which they are out of phase. As such, for manualsummation, the vibration sensors 150 a,b,c,d,e must be connected so thatpositive charge is amplified by the addition of other vibration sensors150 a,b,c,d,e in the circuit rather than being cancelled.

One embodiment of a leak detector 3100 is shown in FIG. 13 connected tothe nozzle cap 15, which is then connected to the fire hydrant 58. Theenclosure 1110 is shown connected by threading 1105 to the enclosurethreading 25 of the nozzle cap 15, although other fastening elementswould be known to one of skill in the art.

The interaction of components of the leak detector 3100 can be seen incloser detail in FIG. 14 . A mating enclosure 3305 is fit around theoutside of the enclosure 1110 and rests against an annular shoulder 3302of the enclosure 1110. A gasket 3350 provides a seal between the matingenclosure 3305 and the enclosure 1110. In some embodiments, the matingenclosure 3305 will have a very tight fit with the enclosure 1110thereby providing some leakage resistance as well.

The antenna 120 and antenna enclosure 320 can also be seen. An antennacable 3125 is seen and is similar to antenna cable 125. Four ferritebeads 3127 a,b,c,d can be seen surrounding the antenna cable 3125.

The leak detector 3100 of the current embodiment includes two circuitboards. One circuit board is a RF board 3136 (similar to RF board 136′)and another circuit board is a DSP board 3137 (similar to DSP board137′). In various embodiments, the RF boards 136′,3136 may be calledcommunication boards and the DSP boards 137′,3137 may be called loggerboards, as various functionality may be included. Although two circuitboards are shown in the current embodiment, components of the RF board3136 may be combined with components of the DSP board 3137 in variousembodiments, and the components may be combined on any number of boardsfrom one to many in various embodiments.

As can be seen, the antenna cable 3125 is connected to the antenna 120on one end and to the RF board 3136 on the other end. The DSP board 3137is connected to the RF board 3136, and the two circuit boards aremounted to the enclosure 1110 in proximity with one another. Althoughnot shown in the current embodiment, in many embodiments, the DSP board3137 and RF board 3136 are encased in potting to prevent electricalshorting in the aqueous environment of the inside of the fire hydrant58. Vibration sensors 150 c,d,e can be seen in the current view of thecurrent embodiment (vibration sensors 150 a,b seen in other FIGs). Inthe current embodiment, vibration sensors 150 a,b,c,d,e may not beencased in potting material, as such potting material may preventdeflection that allows the generation of a current by the piezoelectricmaterial of the vibration sensors 150 a,b,c,d,e. In some embodiments,the vibration sensors 150 a,b,c,d,e may be encased in potting material.Additionally, batteries 3130 a,b and 3131 a,b can be seen incross-sectional view. Bolts 155 c,d,e can be seen fastening vibrationsensors 150 c,d,e, respectively, to the enclosure 1110 (bolts 155 a,band vibration sensors 150 a,b not seen in the current view).

A partition 3410 separates the batteries 3130 a,b,3131 a,b from theelectronic components such as the DSP board 3137, the RF board 3136, andthe vibration sensors 150 a,b,c,d,e. Wire leads (not shown) connect thebatteries 3130 a,b,3131 a,b to the DSP board 3137 and the RF board 3136.The wire leads feed through a hole 3411 defined in the center of thepartition 3410. In various embodiments, a connection mechanism (notshown) is included and provides a quick connect between the batteries3130 a,b,3131 a,b and the electronic components. As such, the batteries3130 a,b,3131 a,b may be replaced if they become defective without theneed to replace the leak detector 3100 in its entirety. As notedelsewhere in this disclosure, the power source for the leak detector3100 of the current embodiment may include batteries, ac power, dcpower, solar, or various other power sources known in the art. In someembodiments, kinetic energy of water in the piping system may be used asa source of power generation.

Another cross-sectional view of the leak detector 3100 can be seen inFIG. 15 . In this view, vibration sensors 150 a and 150 e can be seen.The bolt 155 a can be seen fastening the vibration sensor 150 a into thebore 1159 a in the current embodiment. The five-sensor array of thecurrent embodiment includes one vibration sensor 150 a,b,c,d,e connectedto each post 1155 a,b,c,d,e, each by one bolt 155 a,b,c,d,e. Also seenin cross-sectional view, an enclosure fastener 3162 a (3162 b,c not seenin the current view) is seen fastened into a connection bore 3163 a(3163 b,c not seen in the current view) of the enclosure 1110 to connectthe mating enclosure 3305 with the enclosure 1110. A variety offasteners may be used and would be understood by one of skill in theart, including gluing, welding, sealing with a sealant, or providingmating threading on the enclosure 1110 and mating enclosure 3305, amongother solutions. The arrangement can be seen more clearly in thecross-sectional view of FIG. 16 . Note, leads from the vibration sensors150 a,b,c,d,e have been omitted from view for clarity.

Another embodiment of a leak detection subassembly 4111 is seen in FIG.17 . In this embodiment, the vibration sensors 150 a,b,c,d are stackedin a quartet arrangement such that all four vibration sensors 150a,b,c,d are mounted on one post 1155 b. Also included, vibration sensor150 e acts as a burst or tamper sensor (as described elsewhere in thisdisclosure) and is mounted alone on post 1155 d.

In various embodiments of the current disclosure, the teachings of thedisclosure and various systems as shown may be implemented in variousconfigurations throughout the fire hydrant 58 or various othercomponents of the piping system. In various embodiments, vibrationsensors 150 may be included in various locations within and around thefire hydrant 58 or various other components of the piping system. Forexample, in some embodiments, vibration sensors 150 may be included inthe bonnet of the fire hydrant. In various embodiments, variouscomponents may be included in various locations. For example, vibrationsensors 150 may be included in the bonnet while a power supply such asbatteries 130, 3130 a,b, 3131 a,b may be placed in an enclosureconnected to the nozzle cap 15 or in another removable location such asthe outer surface of the fire hydrant 58.

In addition, various embodiments of the current disclosure may includeintegration with a mesh network or other wireless system. As such, themethods, systems, and apparatus of the current disclosure may include awireless repeater or other wireless integration technology.

Leak detectors 100,100′,3100 may include further ability to senseadditional physical attributes of the system. For example, the leakdetectors 100,100′,3100 may include a pressure sensor, a chlorinesensor, other chemical sensors, gas sensors, nuclear sensors and otherpotential inputs. Such inputs may include lines or bores into theenclosure 110,110′,1110 to connect to the circuit board 135, the RFboard 136′, the DSP board 137′, the RF board 3136, the DSP board 3137,or another circuit board or electronic device or system.

FIG. 18 is a block diagram illustrating an embodiment of a portion of aleak detection system according to various implementations of thecurrent disclosure. As illustrated, the leak detection system of FIG. 18includes a section of pipe 70, which has a leak 72. The system alsoincludes leak detectors 74, which happen to be positioned nearest to theleak 72. Although the leak detectors 74 are shown as being attached toor in contact with the section of pipe 70, it should be understood thatthe leaks detectors 74 may also be connected to an inside surface of thepipe 70 and in contact with the water flowing in the pipe. In otherembodiments, the leak detectors 74 may be connected to an outsidesurface of the pipe 70, on an inside or outside portion of a firehydrant 58, or attached to another portion of a water distributionsystem. Leak detectors 74 may be one of leak detectors 100,100′,3100 invarious embodiments or may be leak detection devices in accord withanother embodiment of the current disclosure as described herein or inaccord with the general scope and purpose of the current disclosure. Theleak detectors 74 communicate sensed signals (e.g., acoustic signals,pressure signals, etc.) to the host 20 via the mesh network 22. Forexample, the network 22 may include relay devices (e.g., using ISMfrequency transmission) for relaying radio signals from the leakdetectors 74 to the host 20. The network 22 in some embodiments may alsoinclude a cellular network, a radio network, a LAN, a WAN, or any othersuitable network. The host 20 may be configured to store signals fromthe leak detectors 74 in a database 76.

The leak detectors 74 may be configured to send acoustic data to thehost 20 on a periodic basis. For example, the leak detectors 74 may beconfigured to provide the acoustic information collected over a two-hourperiod every day at a certain time. The leak detectors 74 may also beconfigured to communicate urgent events, such as an indication of alarge leak or burst. Alarms may be communicated to the host 20 when aburst is detected. Therefore, the leak detectors 74 may be configured todetect both small leaks and large leaks. During the periodic acousticmeasurement times, any indication of a leak may be seen as aninconsistency with historic data. However, any large amount of acousticactivity detected at any time may give rise to an alarm signal forindicating a burst. Since small leaks do not necessarily requireimmediate attention, the reporting of the small leaks can be delayeduntil a designated reporting time. However, a detected burst usuallyrequires a quick response in order that the burst can be attended torapidly.

FIG. 19 is a block diagram illustrating an embodiment of the host 20,shown for example in FIGS. 1, 2, and 18 . In this embodiment, the host20 comprises a processor 80 configured to manage the data and signalprocessing functions of the host 20. The host 20 also includes atraining module 82, a sample request module 84, a communication module86, a timing module 88, graphical user interface(s) 90 (or GUIs), a leakdetector management device 92, and the database 76 shown also in FIG. 18. The host 20 may include any combination of software, hardware, and/orfirmware. For example, a portion of the training module 82, samplerequest module 84, communication module 86, timing module 88, GUIs 90,and leak detector management device 92 may be configured entirely orpartially in software and stored in a suitable memory device (notshown).

The training module 82 may be configured to conduct a training sessionduring a period of time when the leak detectors are first installed andready to be initialized. The leak detectors may “listen” for acousticsignals for a 24-hour period to determine the quietest 2-hour windowduring the day. For instance, external noise from street traffic orother activities may create large amounts of acoustic signals that mightbe sensed by the leak detectors. In fact, some noise may appear to be aleak when sensed. Therefore, quiet times during the day (or night) canbe determined as being adequate times to clearly detect leak activitywithout excessive interferences. The training module 82 may analyze theacoustic information from the plurality of leak detectors 74 disbursedthroughout the system to determine specific wake-up times for each ofthe leak detectors 74. The leak detectors 74 may then be awakened attheir designated times. The sample request module 84 may be configuredto send a signal to the leak detectors 74 at their designated reportingtime to awaken them from a sleep mode. Upon waking the respective leakdetectors 74, the sample request module 84 may then request that theleak detectors 74 detect acoustic signals during the respective 2-hourperiod and then transmit the results to the host 20. It will beunderstood by one of skill in the art that the 2-hour period referencedherein is for exemplary purposes only and is not intended to limit thedisclosure in any way. Time periods may range from thousandths of asecond to many hours, including continuous monitoring, in variousembodiments.

The communication module 86 may be configured to communicate with theleak detectors 74 via radio communications, cellular communications, orother suitable types of communication. The timing module 88 may beconfigured to provide synchronization with the various leak detectors,maintain timing for the processor 80, and maintain time/day information.

The GUIs 90 of the host 20 may be configured to display informationregarding leakage information to the user of the host device 20. Forexample, the GUIs 90 may include color-coded displays to indicate thehealth status of various mains 54/56 of the water distribution system.The GUIs 90 or other similar types of GUIs may also be incorporated withoperator system 14 and/or client system 18 shown in FIG. 1 .

The leak detector management device 92 may be coordinated with softwarein the server 13 to share, monitor, and store leakage information fromthe leak detector nodes within the mesh network 22. The leak detectormanagement device 92 may receive signals regarding the health status ofthe actual leak detectors themselves as well as receive acoustic signalinformation from the leak detectors. The leak detector management device92 may also be configured to determine the probability of leaks based onthe received acoustic information. For example, if the received acousticinformation is significantly different from the historic data receivedby the same leak detector over the past several days, then the leakdetector management device 92 may determine with greater probabilitythat a leak has occurred. Otherwise, if the acoustic information is onlyslightly different from the historic data, a lower probability of a leakcan be determined. In this respect, the leak detector management device92 may provide an indication of the probability of a leak. Thisindication might be presented as a “high probability,” “mediumprobability,” “low probability,” or “no probability” of a leak. In otherembodiments, the indication of probability may be provided as apercentage. For example, it may be determined that according to receivedinformation, the probability of a leak might be 35%.

The database 76 may include a repository for acoustic measurements, suchas acoustic waveforms for each of the various leak detector nodes. Thedatabase 76 may also store information regarding the configuration ofleak detectors 74 within the water distribution system to be able todetermine which leak detectors 74 are considered to be adjacent.Therefore, when two adjacent detectors sense similar acoustic activity,the host 20 may be able to determine the general location of a potentialleak.

FIG. 20 is a block diagram illustrating an embodiment of the leakdetector 74 shown in FIG. 18 , according to various implementations. Asshown, the leak detector 74 comprises an enclosure 101, a sensorassembly 102, and antenna 120. The enclosure 101 may include anysuitable structure for protecting electrical components mounted insidethe enclosure 101 from water and other elements. In various embodiments,the enclosure 101 may be enclosure 110, enclosure 110′, enclosure 1110,or various other configurations in accord with the current disclosure.Although antenna 120 is disclosed, any suitable antenna may be used inaccord with the current disclosure. Sensor assembly 102 may includevibration sensors 150 as described elsewhere in this disclosure or mayinclude various other embodiments of sensors in accord with the currentdisclosure. According to some implementations, the enclosure 101 maycontain a housing that meets IP68 standards. The enclosure 101 includessensor connectors 106 and an antenna connector 108. In some embodiments,these connectors may be contained on a circuit board and in someembodiments these connectors may be included on walls of the enclosure101. Electrical components mounted inside the enclosure 101 andprotected by the walls of the enclosure 101 are a carrier assembly 111and a power supply 112. In some embodiments, the carrier assembly 111includes a sensor interface 114, a processing device 116 (in someembodiments, DSP board 137′ or DSP board 3137), and a communicationdevice 118. The enclosure 101 also includes a diagnostic port 121 thatallows the communication device 118 to have direct contact andcommunication with another device, such as a portable computer orhandheld device. The other device in this respect may be used formonitoring the integrity of the leak detector 74 in the field and forrunning diagnostic tests on the leak detector 74.

In some embodiments, the carrier assembly 111 is a single printedcircuit board with the components of the sensor interface 114,processing device 116, and communication device 118 incorporated on theprinted circuit board (such as circuit board 135 in the embodiment ofFIG. 5 ). In other embodiments, the carrier assembly 111 may includemultiple printed circuit boards with the components of the sensorinterface 114, processing device 116, and communication device 118incorporated on the boards in any suitable configuration (such as RFboard 136′ and DSP board 137′ in the embodiment of FIG. 10 and such asRF board 3136 and DSP board 3137 of the embodiment of FIGS. 13 and 14 ).When the electrical components are disposed on multiple boards,standoffs may be used as needed. Connectors may be used to couple theprocessing device 116 with the sensor interface 114 and communicationdevice 118.

The sensor assembly 102 may include any combination of sensors fordetecting various parameters that may be analyzed to detect the presenceof a leak or large burst. For example, the sensor assembly 102 mayinclude one or more piezoelectric sensors (such as vibration sensors150), acoustic sensors, acoustic transducers, hydrophones, pressuresensors, pressure transducers, temperature sensors, accelerometers, orother types of sensors. According to some embodiments, the sensorassembly 102 includes five sensors, where four sensors are configured todetect small leaks and the fifth sensor is configured to detect a burst.The fifth sensor for detecting bursts may be configured as multiplesensors in some embodiments. According to various implementations, thesensor assembly 102 may include three sensors (i.e., an acoustic sensor,a pressure sensor, and a temperature sensor) and may provide the threemeasurements, respectively, via the sensor connectors 106 to the sensorinterface 114.

The power supply 112 may contain one or more batteries, solar-powereddevices, electrical power line couplers, capacitors, or other powersources or components. When external power is received, additionalconnectors or ports may be added through the walls of the enclosure 101.When batteries are used, the power supply 112 may also include a batterycapacity detection module for detecting the capacity of the one or morebatteries.

The sensor interface 114 acquires the acoustic, pressure, and/ortemperature data from the sensor assembly 102. In addition, the sensorinterface 114 may include amplification circuitry for amplifying thesensed signals. The sensor interface 114 may also include summingdevices, low pass filters, high pass filters, and other circuitry forpreparing the signals for the processing device 116.

The processing device 116, as described in more detail below withrespect to FIGS. 21 and 22A-22C, is configured to process the sensedsignals and determine whether a leak exists or whether the probabilityof a leak exists. The processing device 116 is also configured to logthe acoustic information and save it until a designated time when thehost 20 requests the data.

The communication device 118 may include a modem, such as a cellular orISM-enabled modem to provide network access to the communication device118. Also, the communication device 118 may include a tuning module,such as a GPS timing receiver, for providing an accurate timingreference for the leak detector 74 and for synchronizing timing signalswith other elements of the leak detection system 10. The communicationdevice 118 may be configured to transmit and receive RF signals (e.g.,ISM frequency signals), cellular signals, GPS signals, etc., via theantenna 120. In addition, the communication device 118 may send andreceive diagnostic testing signals with an external device (e.g.,handheld device) via the diagnostic port 121.

FIG. 21 is a block diagram showing an embodiment of the processingdevice 116 shown in FIG. 20 . The processing device 116, which may alsobe referred to as a “logger” device, is configured to detect thepresence of a nearby leak in a section of pipe. As illustrated, theembodiment of the processing device 116 includes a processor 124, asensor data handling device 126, a power assembly 128, a communicationmodule 131, a time/sleep module 132, a leak processing module 134, ahealth status detecting module 139, and a storage module 138. Theprocessor 124 may comprise one or more of a microcontroller unit (MCU),a digital signal processor (DSP), and other processing elements.

The sensor data handling device 126 connects with the sensor interface114 and handles the sensor data to allow processing of the signals bythe processor 124. The power assembly 128 may comprise a power source,which may be separate from the power supply 112. In some embodiments,however, the power assembly 128 may be connected to the power supply112. The power assembly 128 may also be configured to control thevoltage and current levels to provide constant power to the processor124. In some embodiments, the processor 124 may be provided with about3.0 volts DC. The communication module 131 connects with thecommunication device 118 and receives and/or sends signals forcommunication through the communication device 118.

The processing device 116 also includes a time/sleep module 132 forproviding timing signal to the processor 124 and may include a crystaloscillator. The time/sleep module 132 also controls sleep modes in orderto minimize battery usage when the leak detector 74 is not in use. Forexample, the processor 124 may include an MCU that operates continuallyand a DSP that sleeps when not in use. Since the DSP normally uses morepower, it is allowed to sleep in order to conserve battery power.

The time/sleep module 132 may be configured to wake various componentsof the processor 124 at designated times in order that sensor datastored during a previous time may be transmitted to the host 20. In someembodiments, the time/sleep module 132 may wake the leak detector 74 ata certain time during the day, enable the sensor assembly 102 to analyzeand record an acoustic waveform for approximately ten seconds, return toa sleep mode for about ten minutes, and repeat the analysis every tenminutes or so for about two hours. After these waveforms are sensed, theleak detector 74 sends the data to the host 20 and the time/sleep module132 returns the device to a sleep mode until the designated time on thenext day. Separate from the regular sensing schedule, the time/sleepmodule 132 may be configured to wake up the processor 124 in the eventthat a large leak, or burst, has been detected.

The leak processing module 134 may be configured to perform the analysisof the acoustic waveforms and other sensed parameters to determine if aleak has been sensed. The leak processing module 134 can also determinethe probability or likelihood that the sensed data is indicative of aleak. The leak processing module 134 may also be configured toconstantly monitor for a burst, in which case an alarm will be sent. Inaddition to sensing small leaks and bursts, the leak processing module134 may also be configured to detect unauthorized tampering with a firehydrant 58 associated with the leak detector 74. Regarding tampersensing, the leak processing module 134 may be configured to determineif a person is tampering with a pumper nozzle of the hydrant 58, ifthere is an unauthorized flow of water from the hydrant 58, or if thehydrant 58 has been damaged, such as from impact by a vehicle. In somerespects, detecting for tampering may use similar methodology as is usedfor sensing bursts, in that the acoustic waveform may display a quickand pronounced plateau above the normal baseline waveform.

At times, the health status detecting module 139 may be configured tooperate to determine the health or integrity of the leak detector 74using various diagnostic tests. For example, the status may be detectedevery time the leak detector 74 wakes up from a sleep mode, which may berepeated several times throughout a two-hour sensing stage. The healthstatus detecting module 139 may detect the sensor functionality and thefunctionality of other hardware devices to determine if there are anyissues. The health status detecting module 139 can also monitor an MCUand/or DSP of the processor 124, memory of the storage module 138, etc.When issues are discovered during the diagnostic tests, the healthstatus detecting module 139 may set flags to indicate the status of thevarious components of the leak detector 74. These flags may becommunicated to the host 20 at designated times.

The storage module 138 may include flash memory, read-only memory (ROM),random access memory (RAM), or other types of memory. The storage module138 may comprise a database for storing acoustic waveforms. The databasemay include frequency bins for storing current acoustic data as well ashistoric data collected over several days. The processor 124 isconfigured to utilize the stored waveforms to detect the presence orprobability of leaks, bursts, or tampering activity.

FIGS. 22A-22C, in combination, form a schematic diagram showing anembodiment of the processing device 116 shown in FIG. 20 and describedin detail with respect to FIG. 21 . As illustrated in FIG. 22A, theprocessing device 116 comprises amplification circuitry 140 thatreceives input from the sensor assembly 102. For example, inputs 141 arereceived from sensors that may normally be off, but may be enabledduring a regular, intermittent sensing period for detecting small leaks.Input 142 is received from a sensor for detecting an urgent event, suchas a burst or tampering. In this respect, the sensors associated withthe inputs 141 may be normally off, but awakened during a reportingperiod and the sensor associated with the input 142 may be normally onto continuously monitor for bursts or other urgent events. The fourinputs 141 are summed in a summing amplifier 143, passed through a lowpass filter 144, and amplified in a gain stage 145 before being providedto a microcontroller unit (MCU) 196, shown in more detail in FIG. 22B.The one input 142 passes through a gain stage 151 and low pass filter192 and is provided to the MCU 196. A reference voltage VREF 146 is alsoprovided to the MCU 196. Resistors 147 and 148 form a voltage dividerfor providing a battery voltage (+VBATT) to one input of an operationalamplifier 149. An output from the operational amplifier 149 is connectedto a non-inverting input of the op amp 149 and is provided to an analogto digital input (ADC) of the MCU 196. The amp circuitry 140 may alsoinclude an accelerometer 194 for providing additional sensing signals tothe MCU 196. A hydrophone input (HYDROPHONE_IN) is provided from aconnector or interface 195 of the processing device 116. In this case,the hydrophone input is provided to the gain stage 151.

As shown in FIG. 22B, the MCU 196 receives sensed signals from theamplification circuitry 140. The MCU 196 is also connected to a carrierboard connector or interface 195 for communicating with a sensor boardor, sensor interface 114, and/or communication device 118. For example,the MCU 196 may communicate sleep/wake and enable signals with thesensor board via IRQ and GPIO ports. Also, GPS receiving andtransmitting signals may also be communicated via theconnector/interface 195. The MCU 196 may therefore control sleep andwake times for the sensors. A 3.0 voltage is provided to the MCU 196 toallow the MCU 196 to operate continuously. The MCU 196 is connected to acrystal oscillator (XTAL) 198 for providing clock signals. Theprocessing device 116 also includes a serial bus (I2C) forcommunication. The processing device 116, according to some embodiments,also includes a distribution control interface 159 for communicatingcontrol signals with the communication device 118 and a distributioncontrol battery interface 160 for communicating battery control signals.A voltage converter 161 communicates transmit and receive signals with aUART of the MCU 196. A reset control circuit 162 may be used to resetthe MCU 196 using a control switch 163. The MCU 196 includes variousconnections via GPIO, IRQ, and SPI outputs with various components shownin FIG. 22C.

As shown in FIG. 22C, an enable signal (DSP_PWR_EN) is provided from theMCU 196 to a switch 170 (e.g., field effect transistor), which controlsan on/off status of a digital signal processor (DSP) 164. When the MCU196 receives an indication of an urgent event, the MCU 196 turns on theDSP for processing the sensed signals. Power is provided by a batteryvia interface 167 for powering the components of the processing device116. The processing device 116 includes voltage regulators 168 and 169for regulating the power to the DSP 164. A separate crystal oscillator(XTAL) 166 provides clock signals to the DSP 164. A reset signal fromthe MCU 196 may be provided to the DSP 164 via the RESET line to resetthe DSP 164. A I2C_REQUEST line from the DSP 164 to the MCU 196communicates a request regarding the I2C serial bus and the DSP_COMPLETEline indicates that the DSP 164 is finished with its processing andstoring of sensed signals. The processing device 116 also includesmemory devices, such as SRAM, flash, and EEPROM for storing sensor data,software and/or firmware, etc. Latches 171 and 172 are used for storinginformation in an SRAM 173. When a signal along FLASH_PWR_EN is providedfrom the MCU 196, the switch 175 is closed to enable powering of theflash memory device 176 through a buffer 174. Also, a EEPROM 177 isconnected to the I2C line and receives data from the MCU 196 forstorage.

FIG. 23 is a block diagram illustrating an embodiment of the DSP 164shown in FIG. 22C. In this embodiment, the DSP 164 includes a processor180, interfaces 181, regulator 182, battery 183, real time clock 184,program memory 185, data memory 186, audio processor 187, power manager188, pre-amplifier 189, and sensor 190. Each sensor 190 is connected tothe preamplifier 189 which amplifies the signal into audio processor187. In the current embodiment, sensor 190 may be vibration sensor 150or may be another sensor of various types as disclosed herein.

Vibration signals from leak detection are processed in a similar way toaudio signals. As such, the audio processor 187 performs many functionsneeded to process the leak detection data. The signal from the audioprocessor 187 is then fed into the processor 180. Program memory 185drives the DSP's programming. The DSP 164 may store processed signalinformation in data memory 186. The battery 183 is regulated by aregulator 182 to power the processor 180. The battery 183 also powers areal-time clock (RTC) 184 whose data is also fed to the processor 180.The processor 180 controls a power manager 188 which itself controlswhether the DSP 164 goes into a sleep mode. The processor 180 alsoincludes a connection to various interfaces 181. In some embodiments,the interfaces 181 include four analog inputs. However, in otherembodiments, many configurations of the interfaces 181 may be used. Theprocessor 180 may also be connected by both a data line and a controlline to the communication device 118 shown in FIG. 20 . The processor180 includes analog to digital conversion capabilities. The audioprocessor 187 includes analog to digital processing, filter and clippingcapabilities, and a codec. In some embodiments, a global positioningsystem (GPS) receiver may be included with the leak detector 74 and maybe utilized to keep accurate time. The GPS receiver may be included withthe DSP 164, the communication device 118, or on its own in variousembodiments.

FIG. 24 is a graph illustrating a sample of exemplary acoustic datareceived by the processing device 116. This data can be used to helpidentify a leak, wherein a leak is determined by the deviation betweenthe baseline (or “normal” line) and the tested line (or “leak” line). Anexample of a possible leak is highlighted in FIG. 24 within a box,wherein the voltage levels within a certain frequency range areconsiderably higher than normal levels. Since the voltage levels appearmuch higher than normal, the probability that a leak has been detectedis fairly good.

FIG. 25 is a block diagram showing an embodiment of the communicationdevice 118 shown in FIG. 20 . The communication device 118 may beconfigured on a printed circuit board, for example. According to theillustrated embodiment, the communication device 118 comprises anantenna 200 (which may include antenna 120), a transmit/receive switch202, an RF power amplifier 204, an RF low noise amplifier 206, a crystaloscillator 208, a transceiver integrated circuit (IC) 210, amicroprocessor 212, a second crystal oscillator 214, and flash memory216. A battery 218 is configured to power many of the components of thecommunication device 118, including the transceiver IC 210, themicroprocessor 212, the RF power amplifier 204, the RF low noiseamplifier 206, and flash memory 216. The battery 218 may be one or moreof batteries 130,3130,3131, or another battery suitable for use. Invarious embodiments, power sources other than batteries may be used invarious circuitry as disclosed elsewhere herein and known to one ofskill in the art. Crystal oscillators 208 and 214 are connected to thetransceiver IC 210 and the microprocessor 212, respectively. Althoughflash memory 216 is specified, any type of memory may be used with thecommunication device 118.

A data line connects the antenna 200 to the transmit/receive switch 202.RF received data from the antenna 200 is fed into the RF low noiseamplifier 206 and then to the transceiver IC 210. The transceiver IC 210is connected to the microprocessor 212 and to the RF power amplifier204. If RF transmission data is to be sent to the antenna 200 and,thereby, to the host or another remotely located communicator, it istransmitted to the RF power amplifier 204 where it is amplified andtransmitted to the transmit/receive switch 202 and on to the antenna 200for communication.

The microprocessor 212 and transceiver IC 210 include both a two-waydata and a two-way control line. The microprocessor 212 include acontrol line to each of the RF power amplifier 204, RF low noiseamplifier 206, and the transmit/receive switch 202. The microprocessor212 is also connected to the flash memory 216 by both a two-way dataline and by a battery status line, the battery line included so that theflash memory 216 may notify the microprocessor 212 of its power andbattery status. Finally, the microprocessor 212 is connected to the DSP164 shown in FIG. 23 .

The communication device 118 may be configured on various radiotopologies in various embodiments, including point to point, point tomultipoint, mesh networking, and star, among others. The communicationdevice 118 may be configured to communicate in multiple topologies or inone of multiple topologies.

FIG. 26 is a diagram illustrating an embodiment of the carrier board 111shown in FIG. 20 . The carrier board 111 is implemented as a printedcircuit board with the components of the processing device incorporatedthereon, and in some embodiments may also include the sensor interface114 and/or communication device 118 incorporate thereon. In thisembodiment, the carrier board 111 is designed to specifically fit undernozzle cap 15 of fire hydrant 58. The printed circuit board thus has akeystone or muffin shape for fitting within the hydrant cap enclosure.The surface area, according to some implementations, may be about 4.21square inches.

Sensors 222-0, 222-1, 222-2, and 222-3 represent the four normally-offsensors of the sensor assembly 102 that provide inputs 141 to theprocessing device 116. Sensor 224 represents the single normally-onsensor that provides input 142 to the processing device 116. The MCU196, transmission leak detector connector 197, distribution leaddetector connector 159, switches 163 and 175, buffer 174, flash 176, DSP164, latches 171, 172, and RAM 173, shown in FIGS. 22A-22C may bearranged as illustrated in FIG. 26 . It should be understood that otherminor modifications to the positioning of the elements may be madewithout departing from the spirit and scope of the present disclosure.The elements mounted on the printed circuit board are powered bybatteries 225 and 226, although connection to external batteries such asbattery 130,3130,3131 may be possible in various embodiments. Thecarrier board 111 also includes four through-holes 228 for enabling thecarrier board to be mounted within the valve cap of the hydrant 58and/or to standoffs for connection to other printed circuit boards, suchas boards that support the sensor interface 114 and/or communicationdevice 118 if not already incorporated in the carrier board 111.

FIG. 27 is a flow diagram illustrating a method of the leak detector 74at its startup. At installation, the leak detector 74 starts, or powersup, as shown in block 230. The leak detector goes through diagnostictests to check hardware as shown in block 232. For example, the hardwaremay include the batteries (or other power sources), RTC 184, regulator182, communication device 118, sensor assembly 102, audio processor 187,various memory devices (including flash memory 216, program memory 185,and data memory 186), and various processors 180, 212. Other hardwaremay also be checked in other embodiments.

The method of FIG. 27 then proceeds to check software as shown in block234, the software including data I/O, memory storage, programming andprogram flow, and event trigger testing. The leak detector 74 then turnsoff peripherals as shown in block 236, thereafter setting the RTC 184for leak detection wake up as shown in block 238 and sleeping as shownin block 240. The RTC 184 may set the leak detector 74 to awake for leakdetection 2% of the time in the current embodiment. However, otherwakeup intervals may be chosen. Moreover, a 2% leak detection intervalmay include 2% of any time interval. For example, in some embodiments,the leak detector 74 will awaken for a span of 28.8 minutes once everytwenty-four hours. In other embodiments, the leak detector 74 willawaken for a span of six seconds once every five minutes. In bothexample embodiments, the leak detector 74 is awake for only 2% of thetotal time. Various other embodiments may also be used.

Although not shown in FIG. 27 , an indicator light may be included insome embodiments to provide visual affirmation to the installer that theleak detector 74 has been activated and installed and that all hardwareand software has been checked and verified to be in working order. Insome embodiments, the indicator light will be a green LED set to blinkseveral times before the leak detector 74 goes to sleep (step 240).

FIG. 28 is a flow diagram illustrating a method that follows aninitiation stage (e.g., after FIG. 27 ). The method of FIG. 28 may beused during the life of the leak detector 74. Starting in sleep mode asshown in block 250, the method first determines whether the host iswaking up the leak detector 74 from sleep. If yes, the method proceedsto the host event (e.g., FIG. 29 ), as shown by block 256. If no, themethod proceeds to block 254 to determine if the RTC 178 is waking upthe leak detector 74. If no, the method returns to block 250 and theleak detector 74 goes to sleep. If yes, the method proceeds to the RTCevent (FIG. 30 ), as shown in block 258.

Other modes are also possible, although not shown in the method of thecurrent embodiment. In some embodiments, user testing may be performed.In some embodiments, user activated programming may occur. These aretypically performed locally either by wire or by short range radio,although such functions may be performed from a host as well.

FIG. 29 is a flow diagram illustrating a method for a host event, whichoccurs when the host places a call for (i.e., wakes up) the leakdetector 74 to operate. In this method, the first step occurs when theRF circuit (e.g., communication device 118) wakes the DSP 164 as shownin block 264. This may occur when the RF circuit receives a call fromthe host 20 to wake the DSP 164. The processor of the DSP 164 is turnedon as shown in block 266. The DSP 164 receives data from host 20 asshown in block 268. This data may be received by transmission throughthe RF circuit as denoted above. Some of the data received may include aunit ID, location (which may include GPS data or simply a locationcode), RTC data (for synchronizing the RTC 184), time of wake up, timeof data record, length of data record, frame time, frame frequency,total time, sampling frequency, analog to digital resolution, pipinginformation, environment, and frequency data, among others. The DSP 164then may send data to the host 20 as shown in block 270. This data mayinclude any of the data above or any of the following: leak profileidentification data, leak profile, raw signal, manufacturer id, leakhistory, leak status, leak probability, and system hardware and softwarediagnostic data, among others. The method then proceeds to set the RFcircuit for cyclic sleep, as shown in block 272, and then sleep, asshown in block 274.

FIG. 30 is a flow diagram illustrating another method. Referring back toFIG. 28 , if the RTC 184 calls for the DSP 164 to wake up, the methodproceeds to the method of FIG. 29 . In this method, the RTC 184 wakes upthe DSP 164 as shown in block 280. The DSP 164 is turned on as shown inblock 282. The method then proceeds to block 284 to determine if it isthe scheduled leak detection time. If yes, the method reads sensor dataas shown by block 286, after which the method proceeds to block 288. Ifno, the method skips block 286 and proceeds to block 288. Block 288represents the decision of whether it is the scheduled time to recorddata. If yes, the method proceeds to block 290 to record sensor data,after which the DSP 164 sleeps as shown by block 292. If no, the methodskips block 290 and proceeds directly to block 292 to sleep the DSP 164.Recording sensor data as shown by block 290 of FIG. 29 may include anyor all of the following: turning the sensor and codec on, sending codecsettings (including filter settings and sampling frequency), retrievingdata for data recording time, compressing and gathering clipped data,and storing data in memory, among others.

Reading sensor data as shown by block 286 may include any or all of thefollowing: turning the sensors and codec on, sending codec settings(including filter settings and sampling frequency), performing a Fouriertransformation or FFT, determining whether leak data is found,estimating noise, comparing current noise and signal profiles with priorsaved profiles, determining if any significant changes have occurred andflagging significant changes as leaks, determining a probability of aleak, and repeating for the allotted time, among others.

According to various implementations of the present disclosure, leakdetectors and systems and methods for detecting leaks are provided. Insome embodiments, a leak detector may comprise a sensor assemblyincluding at least one sensor configured to sense acoustic signals andat least one printed circuit board coupled to the sensor assembly. Theprinted circuit board may be configured to support a processing devicethat includes at least a microcontroller unit (MCU) and a digital signalprocessor (DSP). The MCU may be configured to continually receiveacoustic signals from the sensor assembly and the DSP may be configuredto remain in a sleep mode except when the MCU wakes the DSP from thesleep mode at predetermined times.

During the predetermined times, the DSP is configured to process thesensed acoustic signals. The DSP may be configured to compare thestrength of the sensed acoustic signals with a baseline waveform andthen determine a probability of a leak based at least on the extent towhich the sensed acoustic signals exceed the baseline waveform. The DSPmay compare the sensed acoustic signals with the baseline waveformwithin a predetermined frequency bandwidth. The leak detector mayfurther comprise a first crystal oscillator coupled to the MCU and asecond crystal oscillator coupled to the DSP. In some embodiments, theat least one printed circuit board is further configured to support asensor interface coupled between the sensor assembly and the MCU.

The sensor assembly may comprise at least an acoustic sensor and apressure sensor, wherein the pressure sensor is configured to detect aburst in a pipe. The MCU may be configured to analyze a high-speedpressure transient profile of the pressure sensor to detect the burst.Also, the MCU may be configured to wake the DSP when a burst isdetected. In addition, the sensor assembly may further comprise atemperature sensor. The leak detector described above may have a sensorassembly that is configured to detect acoustic signals from water pipeshaving a diameter greater than twelve inches. In other embodiments, thesensor assembly may be configured to detect acoustic signals from waterpipes having a diameter less than twelve inches.

The at least one printed circuit board mentioned above may be furtherconfigured to support a communication device for wirelesslycommunicating acoustic signals to a host. The at least one printedcircuit board may comprise a first circuit board and a second circuitboard, the first circuit board configured to support the MCU and DSP,and the second circuit board configured to support the communicationdevice.

The DSP may be configured to convert the acoustic signals to the timedomain using a Fast Fourier transform process. The sensor assembly maycomprise at least a hydrophone that continually senses acoustic signals.The MCU may be configured to correlate acoustic waveforms associatedwith events unrelated to leaks in order to remove any presence of thecorrelated waveforms from the sensed acoustic signals. One method forcorrelating acoustic waveforms may involve sampling a particular areaduring high traffic times of day, using Fourier Transforms to understandwhich frequencies spike at which times of the day, and filtering outthese frequencies from the associated signal. Other methods known in theart or developed in keeping with other aspects of this application ofone of skill in the art may be utilized to provide this correlation. Theleak detector may further comprise memory for storing the acousticsignals and a power source configured to provide power to the processingdevice.

According to a method for detecting leaks, one embodiment includesplacing a digital signal processor (DSP) in a sleep mode, wherein theDSP is incorporated in a leak detector. The method also includesdetermining whether a request is received from a host to awaken the DSPand awakening the DSP when the request is received. Also, it isdetermined whether an urgent event related to a leak in a water main hasbeen detected by a microcontroller unit (MCU) and awakening the DSP whenthe urgent event is detected. The method also includes enabling the DSPto analyze acoustic signals when awakened.

Awakening the DSP as mentioned above comprises the step of turning on aprocessor of the DSP. Turning on the processor of the DSP may compriseutilizing a real time clock to turn on the processor. The method mayfurther comprise the step of forwarding the analyzed acoustic signals toa communication device for communication to the host.

As stated earlier, piezoelectric material must be accurately andrepeatably punched to effect a predictable response curve. As such, FIG.31 displays the punching jig 1200 for punching mounting holes in sensors150,150′. The jig 1200 includes a support 1210, a cup 1220, and a punch1230.

Referring to FIGS. 32 and 33 , the cup 1220 is generally cylindrical inshape. The cup 1220 includes a cylindrical recess 1310 and a bore 1320.Although all features of the cup 1220 are cylindrical and/or circular incross-section in the current embodiment, other configurations areconsidered included in this disclosure. As seen in the view of FIG. 33 ,the recess 1310 and bore 1320 are approximately a constant diameter fortheir entire depth in the current embodiment. Stated differently,neither the recess 1310 nor the bore 1320 include any taper, although ataper may be found in some embodiments. Dimensions included in thecurrent figures should not be considered limiting on the disclosure, asany dimensions sufficient to perform the described function areconsidered included in this disclosure. The dimensions included are forillustration only and provide but one possible configuration.

FIG. 34 displays the support 1210′. FIG. 35 displays the support 1210.Each support 1210,1210′ includes a sensor recess 1810 sized to acceptvibration sensor 150. A bore 1820 is located centrally to the sensorrecess 1810. A cutout 1830 is located in the side of the support1210,1210′. Because the vibration sensor 150 is provided with electricalleads (such as leads 157 a,b) attached to its outer edge, the cutout1830 provides clearances so that the leads 157 a,b will not be crushedinside the jig 1200. The support 1210′ includes a relief edge 1840between the sensor recess 1810 and the cutout 1830 so that the leads 157a,b are not exposed to any sharp edges. Although a flat cutout 1830 isincluded in the current embodiment, any type of cutout 1830 may beincluded in various embodiments so long as the cutout 1830 providesclearance for the leads 157 a,b.

As can be seen with reference to FIG. 35 , the bore 1820 includes anupper portion 1910 and a lower portion 1920. The upper portion 1910includes approximately the same diameter as the bore 1320. The lowerportion 1920 includes a larger diameter than the bore 1320. It shouldalso be noted that the support 1210 includes a taper to the outsideedge, such that the bottom of the support 1210 is smaller in diameter orfootprint than the top of the support 1210. The punch 1230 is shown inFIG. 36 . The punch 1230 includes a head 2310 and a shaft 2320. Apunching edge 2330 is included at the bottom of the shaft 2320. Thepunching edge 2330 is designed to be sharp to effect a clean cut on thepiezoelectric sensors 150. The shaft 2320 is of a diameter slightlysmaller than the diameter of the bore 1320 and the upper portion 1910.The diameter of the head 2310 is larger than the diameter of the shaft2320 which fits into the bore 1320. This can be seen in FIGS. 37 and 38. The diameter of the head 2310 is larger than the diameter of the bore1320 to retain it against the jig 1200.

Referring back to FIG. 31 , the jig 1200 is assembled with the punch1230 inserted into the bore 1320. To create a mounting hole 158 invibration sensor 150, one vibration sensor 150 without a mounting hole158 is placed in the sensor recess 1810. The sensor recess 1810 is sizedto hold the vibration sensor 150 in a specific alignment to effect aprecise bore in the vibration sensor 150 when punched. The leads 157 a,bof the vibration sensor 150 are aligned with the cutout 1830 and feddown the side of the support 1210. The cup 1220 is placed over thesupport 1210 and the vibration sensor 150. The vibration sensor 150 issupported along its entire bottom surface by the support 1210 and isheld in place by the pressure of the cup 1220. Because piezoelectricmaterial may be extremely brittle, the support placed along the entirebottom surface aids in preventing fracture of the piezoelectricmaterial.

To effect a bore such that a mounting hole 158 is created, the punch1230 is first inserted into the bore 1320. Because it is a tight fit,the punch 1230 is located precisely in the center of the vibrationsensor 150. Quick, high-force pressure is applied to the punch 1230. Thepunching edge 2330 comes in contact with the vibration sensor 150,thereby forcing it through the vibration sensor 150 and creatingmounting hole 158 in the sensor 150. The punch 1230 continues throughthe upper portion 1910 and is sized so that punching edge 2330 willextend through the upper portion 1910 and into the lower portion 1920.This gives the blank created as a byproduct of the punching clearance tofall out of the jig 1200. Although the disclosure refers to punching avibration sensor 150 that is produced at low cost, various materials maybe used for the vibration sensor 150 or for various other sensors inaccord with this disclosure. This disclosure contemplates that one ofskill in the art may both create the sensor (through deposition ofpiezoelectric material and a conductor on a base) and punch mountingholes in one process. Nothing in this disclosure is intended to suggestthat these steps must be performed by multiple actors. Additionally, amounting hole may be included prior to the deposition of piezoelectricmaterial or conductor on the base.

This disclosure represents one of many possible assembly configurations.One skilled in the art will understand obvious variations of thisdisclosure are intended to be included, including variations of steps,combinations of steps, and dissections of steps, among others. Wherematerials are chosen for the elements of this assembly, similar materialchoices may also be used and would be obvious to one in the art.

One should note that conditional language, such as, among others, “can,”“could,” “might,” or “may,” unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or steps. Thus, suchconditional language is not generally intended to imply that features,elements and/or steps are in any way required for one or more particularembodiments or that one or more particular embodiments necessarilyinclude logic for deciding, with or without user input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment.

It should be emphasized that the above-described embodiments are merelypossible examples of implementations, merely set forth for a clearunderstanding of the principles of the present disclosure. Any processdescriptions or blocks in flow diagrams should be understood asrepresenting modules, segments, or portions of code which include one ormore executable instructions for implementing specific logical functionsor steps in the process, and alternate implementations are included inwhich functions may not be included or executed at all, may be executedout of order from that shown or discussed, including substantiallyconcurrently or in reverse order, depending on the functionalityinvolved, as would be understood by those reasonably skilled in the artof the present disclosure. Many variations and modifications may be madeto the above-described embodiment(s) without departing substantiallyfrom the spirit and principles of the present disclosure. Further, thescope of the present disclosure is intended to cover any and allcombinations and sub-combinations of all elements, features, and aspectsdiscussed above. All such modifications and variations are intended tobe included herein within the scope of the present disclosure, and allpossible claims to individual aspects or combinations of elements orsteps are intended to be supported by the present disclosure.

Various implementations described in the present disclosure may includeadditional systems, methods, features, and advantages, which may notnecessarily be expressly disclosed herein but will be apparent to one ofordinary skill in the art upon examination of the detailed descriptionand accompanying drawings. It is intended that all such systems,methods, features, and advantages be included within the presentdisclosure and protected by the accompanying claims.

What is claimed is:
 1. A leak detection device comprising: a rigid enclosure in vibrational communication with a component of a water distribution system; a plurality of vibrational sensors disposed within the rigid enclosure configured to sense vibrations conducted from the component of the water distribution system through the rigid enclosure, at least two of the plurality of vibrational sensors connected together by a summation circuit; and a digital signal processing (DSP) circuit disposed within the rigid enclosure and in electrical communication with the plurality of vibrational sensors, the DSP circuit configured to process signals from the plurality of vibrational sensors to detect a leak in the water distribution system, wherein a plurality of rigid posts are disposed on an inside surface of the rigid enclosure, the plurality of rigid posts configured to serve as mounting points for the plurality of vibrational sensors and to provide structural restraint against resonance of the rigid enclosure to reduce distortion from the resonance in the signals from the plurality of vibrational sensors.
 2. The leak detection device of claim 1, wherein the summation circuit is disposed on a circuit board mounted inside the rigid enclosure.
 3. The leak detection device of claim 1, wherein the summation circuit comprises a passive summation circuit configured to amplify in-phase signals from the at least two vibrational sensors and cancel random noise.
 4. The leak detection device of claim 1, wherein at least two of the plurality of vibrational sensors are mounted on a same one of the plurality of rigid posts.
 5. The leak detection device of claim 1, wherein at least one of the plurality of vibrational sensors is monitored through the DSP circuit periodically and another of the plurality of vibrational sensors is monitored continuously.
 6. The leak detection device of claim 5, wherein the continuously monitored other of the plurality of vibrational sensors is used to detect a pipe burst or a tamper event in the water distribution system.
 7. The leak detection device of claim 1, further comprising: a communication circuit disposed within the rigid enclosure and in communication with the DSP circuit, the communication circuit configured to communicate leak detection data.
 8. The leak detection device of claim 7, wherein the DSP circuit and the communication circuit are disposed on at least one circuit board, the at least one circuit board located inside the rigid enclosure and encased in a potting material to prevent exposure to water, the plurality of vibrational sensors not encased in the potting material to prevent limiting of sensed vibrations conducted through the rigid enclosure.
 9. The leak detection device of claim 7, wherein the rigid enclosure is disposed on the inside of a nozzle cap of a fire hydrant.
 10. The leak detection device of claim 9, further comprising an antenna electrically connected to the communication circuit and antenna protruding from the rigid enclosure and the nozzle cap and enclosed in an antenna enclosure made from a different material than the rigid enclosure and the nozzle cap.
 11. A method comprising: providing a leak detection device contained within a rigid enclosure in vibrational communication with a component of a water distribution system, the rigid enclosure comprising a plurality of rigid posts disposed on an inside surface of the rigid enclosure, the plurality of rigid posts configured to serve as mounting points for a plurality of sensors disposed within the rigid enclosure and to provide structural restraint against resonance of the rigid enclosure to reduce distortion from the resonance in sensor data from the plurality of sensors; operating the leak detection device in a sleep state; periodically transitioning, by the leak detection device, from the sleep state to a wake state; upon transitioning to the wake state, recording, by the leak detection device, the sensor data from a first and a second sensor of the plurality of sensors, the recorded sensor data stored in a memory of the leak detection device; after recording the sensor data from the first and second sensors, returning, by the leak detection device, to the sleep state; continuously monitoring, by the leak detection device, a third sensor of the plurality of sensors while in the sleep state and the wake state; and upon detecting a large amount of acoustic activity from the third sensor, raising an alarm indicating a burst pipe or tamper event in the water distribution system.
 12. The method of claim 11, wherein the recording of the sensor data from the first and second sensors is performed by a digital signal processing (DSP) circuit of the leak detection device.
 13. The method of claim 12, wherein the first and second sensors are connected to the DSP circuit by a summation circuit disposed on a circuit board inside the rigid enclosure, the summation circuit comprising a passive summation circuit configured to amplify in-phase signals from the first and second sensors.
 14. The method of claim 11, further comprising periodically retrieving, by the leak detection device, recorded sensor data from the first and second sensors from the memory and transmitting, via a communication circuit, the recorded sensor data to a host for leak detection processing.
 15. The method of claim 11, wherein the rigid enclosure is disposed on the inside of a nozzle cap of a fire hydrant.
 16. A leak detection device, comprising: a rigid enclosure disposed on an inside and in vibrational communication with a nozzle cap of a fire hydrant in a water distribution system; a plurality of vibrational sensors disposed within the rigid enclosure and configured to sense vibrations conducted from the fire hydrant through the nozzle cap and the rigid enclosure, at least two of the plurality of vibrational sensors connected together by a summation circuit; and a circuit board contained within the rigid enclosure, the circuit board including a communication circuit and a digital signal processing (DSP) circuit in electrical communication with the plurality of vibrational sensors, the DSP circuit configured to record and process sensor data retrieved from the at least two of the plurality of vibrational sensors to produce leak detection data and the communication circuit configured to communicate the leak detection data to a host, wherein the rigid enclosure comprises a plurality of rigid posts disposed on an inside surface of the rigid enclosure, the plurality of rigid posts configured to serve as mounting points for the plurality of vibrational sensors and to provide structural restraint against resonance of the rigid enclosure to reduce distortion from the resonance in the sensor data from the plurality of sensors.
 17. The leak detection device of claim 16, wherein at least one of the plurality of vibrational sensors is monitored through the DSP circuit periodically and another of the plurality of vibrational sensors is monitored continuously.
 18. The leak detection device of claim 17, wherein the leak detection device is configured to, upon detecting a large amount of acoustic data from the continuously monitored other of the plurality of vibrational sensors, communicate a pipe burst or tamper event to the host through the communication circuit. 